This invention relates to improvements in and relating to separating membrane or diaphragm type electrolytic bath arrangements.
For carrying out the electrolysis of aqueous solution of solutes such as common salt, there are three main process modes classified as non-diaphragm mode electrolysis, diaphragm mode electrolysis and mercury electrolysis. As the separating membrane or diaphragm usable in the second of the above three known electrolytic processes, ion exchange membranes are rather preferably employed in the recent decade, in addition to porous membranes or diaphragms, as is well known to any person skilled in the art. Although the membrane or diaphragm electrolysis may be defined under occasion as different from the ion exchange membrane electrolysis by those skilled in the art, the membrane or diaphragm electrolysis as used herein and in the appended claims should be understood as including these both kinds of electrolysis.
For improving the energy efficiency in the membrane electrolysis, the kind of the membrane and the structure and arrangement of the electrolytic bath, as well as the material and structural arrangement of the electrodes must be jointly and specifically taken into account.
Among these factors, it should be noted that various and different proposals have long been made as for the structure and arrangement of component electrodes.
However, these proposals concern mostly with either anodic or cathodic electrode per se and it is rate to provide the overall and combined arrangement improvement for the anode and cathode jointly and as a whole.
In order to attain improvement in the electric energy efficiency, it is necessary to reduce the electrolytic service voltage for the electrolysis. For satisfying this requirement, the interelectrode distance must be reduced to a possible minimum, the developed gas or gases must be dissipated or removed as quickly as possible from the related electrode, so as to utilize the overall electrode surface in the most effective way. However, in practice, these requirements can not practically be satisfied with use of the currently available electrodes.
As the cathodic electrode, a plain woven soft steel wire net or a perforated soft steel plate or the like has hitherto been utilized preferentially. As an example, partially rolled wire nets, of 23 mm dia., 6 mesh, are being used representatively for almost all currently available membrane electrolytic bath units utilizing the deposit type asbestos separating membranes. It should be noted at first, however, in this case, that the plane parallelism of the wire net material as a whole is worse than desired, and thus, the electrode made therefrom represents as rough as plus/minus 2 mm at the minimum in its plane preciseness, thereby encountering with a substantial difficulty in minimizing the interelectrode distance and inviting a substantial uneveness thereof, which means naturally a grave defect in the art. When trying to minimize the inter-electrode distance beyond the normally allowable minimum dimensional limit in spite of the above uneveness and difficulty, unavoidable contact will occur locally among the anode, membrane and cathode at smallest interelectrode distance, thereby the membrane being subject to disadvantageous mechanical vibration and oscillation causing the membrane to slacken.